Method of rerecording sound



NIW. 26, 1935. t 1 v MARESCA 2,022,473

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F INVENTOR .1.v.MAREscA BY W42? M144,

Nov. 26, 1935. J. v. MAREscA 2,022,473

METHOD OF RERECORDING SOUND Filed Aug. 27, 1931 2 sheets-sheet 2 NVENTOR A MARESCA n v BY` 'ATTORNEY Patented Nov. 26, 1935 METHOD oF RERECORDING soUND James V. Maresca, Los Angeles, Calif., assgnor to Radio-Keith-Orpheum Corp., a corporation of Maryland Application August 27, 1931, Serial No. 559,651

-11 Claims. (Cl. 179-1003) 'I'his invention relates to the rerecording of sound from one sound record to another and has for its principal object the provision of an iinproved means and method of rerecording sound in a manner to permit the raising of the level of certain parts of the record, such as dialogue and the like.

`The present invention is similar in some respects to that disclosed in a copending application of Hugh McDowell, Jr., Serial No. 494,215, led November 8, 1930, patented April 26, 1932, Patent No. 1,855,196, and assigned to the same assignee as the present application.

In the aforesaid copending application is disclosed means whereby the greater part of the normally clear portion of the sound record is eliminated in order to permit full modulation at a given sound intensity, thus permitting the modulation to fall to its natural minimum and rise to its natural maximum without the production of objectionable ground noise.

The present invention differs from that of the copending application in that the normal sound record -with its White portion unshaded, is utilized to control the operation of the rerecorder, and means are provided for shading more or less of the clear portion of the film during rerecording. 'I'his permits the level of any desired part of the sound record, such as dialogue, to be raised without undue amplification of the ground noise.

My invention will be better understood from the following description when considered in connection with the accompanying drawings, and its scope will be Vpointed out in the appended claims.

Referring to the drawings:

EFig. 1 is a diagrammatic illustration of a rerecording equipment wherein my invention -has been embodied;

Fig. 2 illustrates a form of anti-ground noise device suitable for use in connection with the rerecording apparatus;

Fig. 3 is a wiring diagram illustrating certain features of the anti-ground noise device of Fig. 2; and,

Fig. 4 illustrates a section of the rerecorded sound track.

The apparatus illustrated by Fig. 1 includes a projector I9 of the usual type, a photo-cell amplifier II, a voltage amplifier I2, a power amplifier I3, a rectifier I4, and an anti-ground noise device I5. From the photo-cell amplifier II audio current is supplied to a recorder I6 through a recording amplifier I1. For purposes of monitoring, the output circuit of the power amplifier I3 is connected to a loudspeaker I8 which is preferably of the electro-dynamictype.

The projector III is of any well-known type including the'usual light slit and optical system. The anti-ground noise device I5 is similar in most respects to that disclosed by the aforesaid co- 5 pending application.

As shown more clearly in Fig. 2, it includes the casing I9 which is adjustably mounted on the frame of the projector I0, and is provided with terminals 20, 2l and 22. It also includes a shut- 10 ter or shading member 23 biased to'a predetermined position by means of a spring 24, and arranged to cover a part of the light slit 25 of the projector ID. The normal position of theA shutter 23 with respect tothe light slit, is determined l5 by adjustment oi the thumb screw 26 which determines the distance between the casing I9 and the projector III.

The connections of the anti-ground noise device I5 to the photo-cell of the amplifier II, are 20 shown in Fig. 3. It will be noted that the photocell is connected to the anti-ground noise device through the amplifiers II, I2 and I3, and the rectifier I4,"and that this device is provided with a core member 21 upon which are wound the 25 field coil 28 and an audio current coil 29, the latter coil being connected to the rectifier I4 through its end terminals, and being grounded connection of the coil, and a resistor 32.

In the operation of the apparatus the shutter 40 23 moves in accordance with the input of the .amplier.circuit, moving nearer the clear edge lof the sound track to accommodate the peaks of modulation on the film, and moving farther away from this edge when the percentage of modula- 45 tion is reduced. Since the vibration of the shutter 23 is in exact accordance with the direct current impulses of the rectifier I4, it therefore permits the transmission of light through the slit 25 only to the extent required to permit the peak 50 modulation to be recorded. The type of record produced is illustrated in Fig. 4 wherein the sound record is indicated at M, and the shading due to the shutter 23 is indicated at N.

As will be apparent to those skilled in the art,

the present invention has the advantage that the sound level of dialogue and the like m-ay be raised without the production of excessive ground noise, this result being due to the fact that the normally clear portion of the sound record is shaded in a manner to prevent the amplification by the amplifiers H and I'l of the larger part of the ground noise which would otherwise become excessive upon increase in the amount of amplification during the rerecording of sound of comparatively low intensity.

Having thus .described my invention and the operation thereof, what I claim isz:

1. The method of rerecording sound .from a record comprising normally clear and opaque portions which includes reproducing sound impulses from said record, raising the sound impulse level during the rerecording of predetermined sections of said record, shading the normally clear portion of said sections to reduce the ground noise impulses which .other-Wise would have been reproduced `during said Areproduction from said sections, and recording `lsaid impulses.

2. The method of rerecording sound from a record comprising Anormally clear and yopaque portions which includes reproducing audio impulses from said record, raising :the sound -impulse level Iduring the rerecording of the dialogue -sections of said record, shading the normally clear portion of said sections to reduce the ground noise impulses which would otherwise have been reproduced and rerecorded from said sections, and recording said audio 'impulses 3. The combination :of means for directing light through a phonophotographic record whereby it is modulate-d in Aaccordance with a sound record, means for converting `said modulated light into electrical impulses, means `for amplifying said modulated impulses, means for recording said ampliiied modulated impulses, `and `means operated by and -in :accordance with said impulses Varying said light in accordance with the 'level of the recorded sound.

4. The combination of means `for directing light through va phonophotographic recordwhereby it is modulated in accordance with a sound record, means for converting -said modulated light into electrical'impulses, means for amplifying said modulated impulses, means for Mrecording said amplified modulated impulses,imeans for rectifying said impulses, and means operated by and in accordance withsaid .rectified impulses to vary said ,light .in accordance with the level of the recorded sound.

.5. The combina-tion of Ya :projector including 1a light slit projecting a light .through -a sound record Iwhereby v-saiid Ilight is :modulated by said record, means for rconverting .said :modulated light 'into electrical impulses, Vmeans =for vampliying said impulses, means for .recording said impulses, and means :in cooperative relation `with ,said 'recording means :and responsive to :said :am-

plied impulses for varying the effective length of said slit.

6. The combination of a projector including a light slit projecting a light through a sound record whereby said light is modulated by said record, means for converting said modulated light into electrical impulses, means for amplifying said impulses, means for recording said impulses, and means in cooperative relation with said recording means and arranged to vary the effective length of said slit in accordance with the level of said impulses.

7.1'1he method of re-recording sound from a record comprising normally clear and opaque portions which includes reproducing sound impulses from said record, shading the normally clear portions of said record to reduce the ground noise impulses otherwise reproduced from said sections, recording said reproduced impulses and shading the portions of the record so produced in .accordance with the sound recorded thereon.

B. The method of re-recording sound from a record :comprising normally .clear and opaque portions `which .includes passing light through said record, producing amplied electrical impulses in accordance with the light passed by said record, rectifying said impulses, shading the clear portion of said record in yaccordance with said `rectified impulses `to reduce the ground noise impulses otherwise reproduced from said sound record, `recording said reproduced impulses, and shading the normally clear portion o1" the record of said reproduced impulses.

Z9. `Apparatus of ,the class described comprising a photoelectric sound reproducer, means in said .reproducer ,for masking the clear portions of a :sound :record reproduced therein, means for amplifying impulses from saidreproducer, means for :photographically recording the `an-ipliiled impulses, and ,means for Vmasking pthe portion of the soundtrack not occupied 'by .said recorded impulses.

l0.. The :method `of making sound records com- 4prising electrically reproducing a sound record :from an ordinary soundtrack not of the antimeans for reproducing sound impulses from a f" photographic sound record, means for shading :the `normally clear `portions of said record to reduce the ground noise impulses otherwise rc- :produced from said portions, means for recording 'said `reproduced impulses, and means for shading the portions of the record produced in accordance with the sound recorded thereon.

JAMES V. MARESCA. 

